Device and method for controlling a vehicle drive

Abstract

Method for operating a propulsion system of a vehicle, wherein the propulsion system comprises an internal combustion engine (60), comprising the steps: Determining an expected end of journey (tA) or a subsequent start of journey (tNS) of the vehicle by estimating the expected end of journey (tA) and / or the subsequent start of journey (tNS) based on stored usage data of the vehicle or by inputting the expected end of journey (tA) and / or the subsequent start of journey (tNS) at a user input interface (22''); Determining a minimum state of charge (S) of a vehicle battery (82) that it should have at the end of the journey (tA) or at the start of the following journey (tNS) by specifying a higher minimum state of charge (S) at low performance given by low temperatures than at comparatively higher temperatures; Operating the internal combustion engine (60), which is equipped with a generator (70) to charge the battery (82), according to an operating strategy whereby a state of charge (I1, I2, I3) resulting from the operating strategy at the end of the journey (tA) or at the start of the following journey (tNS) is at least as large as the minimum state of charge (S) ; where the minimum charge state (S) is determined based on meteorological data that represent a temporal progression of air temperature, based on received data, which represent a predicted air temperature at the determined end of the journey (tA) or at the subsequent start of the journey (tNS), or based on a combination thereof.

Description

[0001] It is well known that vehicles with an internal combustion engine require not only the kinetic energy of the internal combustion engine but also electrical energy to operate. In addition to devices directly required to operate the internal combustion engine, such as the ignition, engine management, starter, and others, a vehicle contains numerous consumers that require electrical energy. These electrical consumers, and especially electric auxiliary drives such as those used in hybrid vehicles, can cause the state of charge to drop to a low level, especially if an alternator is not generating sufficient power.

[0002] Until now, well-known solutions have been used, according to which the alternator and / or the battery are sufficiently dimensioned to avoid an insufficient state of charge. Since this involves considerable effort, one object of the invention is to ensure the supply of electrical energy to a vehicle in a simple manner.

[0003] The document DE 10 2010 018 447 A1 describes a method for controlling a drive train, wherein the internal combustion engine is not started while driving despite a low charge state if the vehicle is located near locations that make it likely that the vehicle will be switched off shortly.

[0004] The document DE 10 2013 201 745 A1 describes a system for controlling the charge level of a hybrid vehicle, whereby the charge level is set in such a way that even during long upcoming downtimes, sufficient energy remains available to start the combustion engine.

[0005] From DE 10 2009 028 922 A1 a method for operating a hybrid vehicle is known, wherein the hybrid control takes into account at least one charge state of an energy storage device and determined position data of the hybrid vehicle in such a way that a minimum charge state of the energy storage device is not undercut.

[0006] DE 10 2012 015 949 A1 discloses a method for controlling the charging operation of an electric motor vehicle, wherein a temporal course of a charging process is determined as a function of predictive, time-related usage information for the motor vehicle.

[0007] DE 10 2009 046 991 A1 discloses a method for improving the performance of a traction battery during the start-up phase of an electric vehicle. It is known from this that the output power of numerous battery types is reduced at low temperatures. Disclosure of the invention

[0008] The above-mentioned object is achieved by the features of the independent claims. Advantageous embodiments result from the features of the dependent claims and from the features of the following description.

[0009] In order to avoid having insufficient energy for starting at the end of a journey in the event of an unbalanced energy balance, i.e., an overall decreasing state of charge, it is proposed to maintain a minimum state of charge as a lower limit by generating electricity using an internal combustion engine that drives a generator. This minimum state of charge refers to the end of a journey, i.e., the end of a current journey, or to the start of a journey following this end. The end of the journey and / or the start of the subsequent journey is estimated (in the sense of determining prospective data), so that a minimum state of charge is not maintained at all times, but rather the operation of the internal combustion engine is focused on the end of the journey and / or the start of the subsequent journey.

[0010] This ensures that if the charge level decreases during the journey (e.g., when driving slowly and consumers such as lighting, air conditioning, or heating are running at high power), the vehicle does not break down because there is insufficient electrical energy available to restart the combustion engine. An operating strategy, according to which the drive is operated, corrects the imbalanced energy balance of the battery or the insufficient charge level at the end of the journey or the subsequent start of the journey. The operating strategy relates to the operation of the combustion engine and, in particular, to the operation of the generator, for example, its excitation current or the mechanical power consumed by the generator.

[0011] A method for operating a vehicle drive is therefore described, wherein the drive comprises an internal combustion engine. The drive can thus be a conventional internal combustion engine drive or a hybrid drive that, in addition to an internal combustion engine, has an electric motor that can generate traction power.

[0012] First, the expected end or subsequent start of the vehicle's journey is determined. This can be done via input or, as explained below, based on other data, in particular learned reference data.

[0013] Furthermore, a minimum charge level of the vehicle's battery is determined, which it should have at the end of the journey or at the start of the next journey. The minimum charge level is therefore only a constant that is retrieved in a specific case and can also depend on other parameters, as explained below.

[0014] The combustion engine, which is configured to charge the battery by means of a generator, is operated according to an operating strategy. The operating strategy is designed such that a state of charge at the end of the journey or at the subsequent start of the journey results that is at least as high as the minimum state of charge. The operating strategy can relate, particularly in hybrid drives, to the operation of an electric machine of the drive and to the operation of the combustion engine of the drive. Furthermore, the operating strategy can also relate to the operation of the generator, in particular to its absorbed mechanical power or, in particular, to the torque with which the generator operates (at a certain speed). Furthermore, the operating strategy can relate to the combustion engine alone, in particular to its speed.The operating strategy determines the electrical power that the combustion engine generates using the generator (which can be designed as an alternator or as a starter generator).

[0015] The expected end of the journey and / or the subsequent start of the journey is estimated based on stored vehicle usage data. Alternatively, the expected end of the journey and / or the subsequent start of the journey is entered, in particular via a user input interface. The usage data is preferably stored in the vehicle, but can also be stored in a mobile or stationary electronic data storage device, such as the memory of a mobile device, a laptop, a central computer, or similar. The usage data is preferably stored encrypted and / or can only be accessed by entering a correct password or another verification method (e.g., fingerprint scanning).The expected trip end and / or the subsequent trip start may first be estimated, subsequently displayed via a user interface, and may be corrected according to user inputs received at the user input interface (which may be part of the user interface) to be used as corrected data when operating the internal combustion engine.

[0016] The usage data is, in particular, specific to a driver, to the respective battery states, to a day of the week, to a time of day, to the respective season, to a (particularly entered) route, for example of a navigation device, to an entered destination and / or to a location of the vehicle. Different or individual usage data can therefore be provided and linked to different drivers, battery states, days of the week, groups of days of the week (weekends, weekdays), times of day, seasons, routes, destinations and / or locations. Battery states are referred to as states of charge (SOC) or aging states (SOH, state of health) of the battery. Alternatively, the expected end of the trip and / or the subsequent start of the trip can be received via a user input interface.The user input interface can be part of a user interface that also includes a user output (particularly graphical). The user output can display several possible dates or times, with one of these dates or times being selected and / or modified according to a user input.

[0017] Furthermore, the minimum state of charge can be determined based on weather data (current or forecast), from which the temperature at the start of the subsequent journey can be determined. This makes it possible to determine (at least) one battery operating parameter (SOC, SOH, temperature) that is directly linked to the battery's performance (during a start-up process). The higher the battery's performance (i.e. the higher the SOC, the SOH or the higher the temperature if below a maximum operating temperature), the lower the minimum state of charge. The lower the performance or the parameters linked to it, the higher the minimum state of charge. The minimum state of charge is therefore adapted to the battery's performance, in particular to the temperature or the SOC of the battery at the start of the subsequent journey.

[0018] According to the invention, the minimum state of charge is determined based on meteorological data that represent a temporal progression of an air temperature, based on received data that represent a forecast air temperature at the determined end of the journey or the subsequent start of the journey, or based on a combination thereof. A battery model can be used that links the maximum available power, the internal conductance, or the short-circuit current according to the electrochemical properties of the battery with the SOH, the SOC, and / or the temperature of the battery. The battery model can be stored based on parameters of a function or a look-up table, or a learning link can be provided that reproduces the model based on empirical data that is used to learn the link. The battery model can therefore be complex or simplified as a simple assignment of values, for example as a look-up table.

[0019] Therefore, if low performance is detected, for example due to low temperatures (e.g., below 0°C or below -20°C), due to advanced aging, or due to low short-circuit current, low maximum power, or low internal conductance of the battery, a higher minimum state of charge is specified than for higher temperatures or a non-advanced aging state, or than for a higher short-circuit current, maximum power, or internal conductance. These parameters can also be linked to determine a value for the battery's performance, which in turn is linked to the minimum state of charge according to a decreasing relationship (in particular, a monotonically or strictly monotonically decreasing relationship).

[0020] In particular, the minimum state of charge is determined based on a predetermined relationship between the minimum state of charge and a predicted temperature at the (subsequent) start of the journey. The minimum state of charge is greater at a lower temperature than at a comparatively higher temperature. The relationship between the minimum state of charge and the temperature increases with decreasing temperature, with an increasing gradient. This takes into account that batteries are particularly sensitive to low temperatures. In particular, at temperatures lower than a threshold temperature such as 0°C, -10°C or -20°C, the minimum state of charge can be increased by a predetermined value in order to take into account the poor cold start behavior of batteries. This predetermined value can depend on the SOH, whereby for a first SOH value the predetermined value is lower than for a second SOH value that is lower than the first SOH.A high SOH value indicates low aging, while a comparatively low SOH value indicates high aging. The SOH value can, in particular, be the current capacity relative to the nominal capacity.

[0021] The minimum state of charge is preferably determined based on a predefined relationship between the minimum state of charge and the state of aging (SOH) of the battery. The minimum state of charge is greater with greater aging than with comparatively less aging. The relationship between the minimum state of charge and the state of aging increases with increasing aging, particularly with increasing aging. This takes into account the reduction in battery performance with increasing aging, particularly the progressive decline in performance (internal conductance, short-circuit current, maximum available power) with advancing aging.

[0022] The operating strategy, which defines the operation of the combustion engine (and / or generator) until the end of the journey, preferably takes into account journey parameters, parameters of consumers in the vehicle, and / or generator parameters. These parameters are taken into account by adjusting the operating time, mechanical power, torque, speed, fuel supply rate, number of active cylinders, cylinder stroke, and / or operating mode of the combustion engine based on the parameters with the aim of maintaining the minimum state of charge at the end of the journey or the start of the subsequent journey. Alternatively or additionally, these parameters are taken into account by adjusting the excitation current, the ratio of input speed on the one hand to power, current, or voltage on the other hand, a target output voltage, or an output current of the generator based on the parameters with the aim of maintaining the minimum state of charge at the end of the journey or the start of the subsequent journey.The generator may include an output regulator or a charge regulator whose operating parameters are set with this goal in mind.

[0023] The parameters taken into account by the operating strategy are in particular: - a charging rate according to which the battery is charged by the generator from the combustion engine, - the end of the journey, - the time until the end of the journey, - the distance to the end of the journey, - an estimated electrical consumption until the end of the journey - an (estimated) consumption for each subsequent run after the journey is taken into account, - road condition information and / or traffic condition information for the route ahead until the end of the journey, and / or - a predicted battery temperature at the end of the trip (or at the start of the following trip).

[0024] The operating strategy takes the aforementioned parameters into account in such a way that different operating strategies are used for different parameters. The operating strategy can be specified by an energy value that characterizes the energy delivered by the generator or also the power, whereby the energy or power delivered by the generator results from operating parameters of the generator and / or the combustion engine that drives it. The higher the charging rate, the closer the end of the trip, the shorter the time until the end of the trip, the shorter the distance until the end of the trip, the lower the estimated electrical consumption until the end of the trip, the lower the consumption for each follow-up run, the better the road condition and / or traffic condition and / or the higher the predicted battery temperature at the end of the trip (or at the subsequent start of the trip), the lower the energy value.The smaller the energy value, the lower the power of the combustion engine or generator, the lower the excitation voltage or current, and / or the shorter the operating time of the combustion engine (in hybrid drives).

[0025] Follow-up times are the process steps of the vehicle after it has been parked, such as a "follow me home" function (which switches on the vehicle's lights for a certain period of time after the vehicle has been parked), a radiator run-on time, or the power consumption of the vehicle's electrical system when the vehicle is parked, such as standby consumption of consumers such as the clock, immobilizer, alarm system and the like.

[0026] The battery, whose minimum charge level is determined, supplies energy to start the combustion engine at the start of the journey. The battery also supplies the vehicle's electrical system with energy while the vehicle is moving and, if necessary, when the vehicle is parked. In hybrid drives, the battery can supply energy for the vehicle's traction while the vehicle is in operation. In hybrid drives, in addition to the battery whose minimum charge level is determined, a traction battery can also be used to supply energy for the vehicle's traction, such as a high-voltage battery. The battery can have a nominal voltage of 12 V, 14 V, 24 V, or 48 V, while the traction battery has a nominal voltage of > 300 V (approximately 350, 360, 380, or 400 V).

[0027] The operating strategy is preferably defined based on an operating time of the combustion engine, which is longer the greater the difference between a current state of charge and the minimum state of charge. The state of charge resulting from the operating strategy at the end of the journey is forecast based on the product of the operating time and the charging rate of the generator and the battery, less a forecast amount of energy that will be absorbed by the vehicle's electrical consumers until the end of the journey, and based on a current state of charge. The forecast amount of energy is calculated from the operating time (until the end of the journey) multiplied by an electrical consumption value (i.e. a power value) of the vehicle. This consumption value can be predetermined, can be recorded as the (averaged) sum of the power of the active consumers, or can be calculated or forecast in another way.Instead of, or in combination with, the operating time of the combustion engine as a parameter that determines the operating strategy, the combustion engine speed, the combustion engine torque, the ratio of the generator's input speed to its output power, or the generator's excitation voltage or current can also be used. This increases the battery's state of charge to meet the minimum state of charge at the end of the trip or at the start of the subsequent trip.

[0028] Another way to maintain the minimum state of charge is to limit the power of the consumers. The function of electrical consumers that are not safety-relevant for the operation of the vehicle is limited if the sum of the current state of charge and the amount of electrical energy determined based on the operating strategy deviates from the minimum state of charge by more than a predetermined tolerance value. The tolerance value specifically stipulates that the amount of energy produced by the generator until the end of the journey is initially increased, and only then, as a subsequent step, if this measure does not result in compliance with the minimum state of charge, is the power of the consumers reduced. The tolerance value can be reduced as the end of the journey approaches.Non-safety-relevant devices include, in particular, (electric) heating, window heating elements, entertainment electronics, or chargers for portable devices. The functionality of the devices can be restricted, but this can be indicated on a display with the option of reversing the restriction (at least for selected devices) upon receipt of a corresponding input. Furthermore, the restriction of the function can initially only be displayed and not implemented, with the restriction being restricted for the affected devices or only for selected devices based on a subsequent user input.

[0029] Finally, a device for controlling a drive of a vehicle is described, wherein the drive comprises an internal combustion engine.

[0030] The device comprises a start prediction unit configured to determine an expected end of a journey or a subsequent start of a journey of the vehicle. The device further comprises a minimum charge prediction unit configured for the step of determining a minimum state of charge of a battery of the vehicle that said battery should have at the end of the journey or at the subsequent start of the journey. The device also comprises an operating strategy specification unit connected downstream of the start prediction unit and the minimum charge prediction unit. The operating strategy specification unit is configured to determine an operating strategy that results in a state of charge at the end of the journey or at the subsequent start of the journey that is at least as high as the minimum state of charge. Finally, the device comprises a control unit connected downstream of the operating strategy specification unit.The control unit is configured to control the combustion engine (and / or the generator) according to the operating strategy. Brief description of the drawings The Fig. 1 shows a time course diagram suitable for explaining the method and the Fig. 2 shows an embodiment of a device for controlling a drive of a vehicle in a symbolic manner. Detailed description of the drawing

[0031] The Fig. 1 shows a time course diagram of a state of charge SOC over time t, where the curves I1 and I2 each represent an actual state of charge compared to a minimum state of charge S.

[0032] Before the time tP, the actual state of charge decreases because the electrical consumers receive more power than is fed in by the generator, or because the combustion engine is switched off and thus no electrical power is fed in by the generator (apart from possible recuperation power), while the consumers draw power from the on-board network and thus from the battery.

[0033] At time tP, the expected end of the journey and / or the subsequent start of the journey is determined. Furthermore, the minimum state of charge is determined at time tP. The minimum state of charge can also be determined before the expected end of the journey tA and / or the subsequent start of the journey tNS. It is therefore recognized at time tP that the state of charge must be increased in order to have a state of charge not below the minimum state of charge S at time tA or tNS. At time tP, the charging power is therefore increased or the combustion engine is switched on, whereby the state of charge increases according to curve I1. At time tA, due to the charging power, which reflects the gradient of I1, and the time period up to tA, an actual state of charge is reached that is above the minimum state of charge S. In the solid curve I, it is further assumed that no power is consumed from tA until time tNS and therefore no follow-up charges discharge the battery.

[0034] The alternative curve extension in dotted line, which follows curve I1, shows the effect of lag. Starting at time tA, the battery is discharged (through loads as mentioned above, or through leakage currents, or through self-discharge, which can also be considered "loads"), so that the dotted line following I1 is already below the minimum state of charge shortly after tA, and at time tNS there is insufficient energy left to start the combustion engine.

[0035] Curve I2 takes into account the lag, i.e., leakage currents, or self-discharge. Therefore, starting at time tP, a higher charging rate (i.e., generator charging power) is selected, so that the state of charge at time tNS is above the minimum state of charge, even though the state of charge decreases starting at time tA. This decrease is taken into account when calculating the operating strategy.

[0036] Curve I3 shows another possible state-of-charge curve for hybrid drives. Up to time tP, the drive is operated purely electrically, whereby the state of charge continuously decreases. At time tP, it is determined that at time tA, the state of charge must be at least as high as the minimum state of charge (discharges and consumers from time tA onwards are not considered here for clarity). Therefore, from time tP onwards, the combustion engine is switched on, which charges the battery according to the gradient between tP and time tE. At time tE, the battery reaches a state of charge significantly above the minimum state of charge.

[0037] In particular, when the combustion engine is switched off at time tE, the state of charge is greater by an amount than the minimum state of charge S, which is sufficient to bring the vehicle to its destination purely electrically. The decrease in the state of charge from time tE results from the electrical consumption by the electric traction and the other electrical consumers. The operating strategy, i.e. the duration between tP (switching on of the combustion engine) and tE (switching off of the combustion engine), is dimensioned such that during this time the state of charge has increased by the difference between the minimum state of charge and the state of charge at time tP, plus the state of charge difference associated with purely electric operation between tE and tA (= amount of energy for electric travel from tE to the destination).It can be seen that despite the combustion engine being switched off at time tE until the destination is reached at time tA, the state of charge at time tA is not below the minimum state of charge.

[0038] The Fig. Figure 2 shows a symbolic embodiment of the device 10 described here for controlling a vehicle drive. The device is particularly suitable for implementing the method described here.

[0039] The device 10 has a start prediction unit 20. This is configured to determine an expected end of a trip or a subsequent start of a trip of the vehicle. The start prediction unit 20 can be connected to an internal memory 22 or to a memory 22' external to the device 10, wherein the times of previous trips are stored in the respective memory in order to deduce the end of the current trip (or the subsequent start of the trip). An expected end of the trip tA and / or the subsequent start of the trip tNS can be received via a user input interface 22'' (external to or not part of the device). For this purpose, the device has a connection to which the user input interface 22'' can be connected.

[0040] The device 10 further comprises a minimum charge prediction unit 30. This is configured to determine a minimum charge level of a vehicle's battery that it should have at the end of a journey or at the start of the subsequent journey. The minimum charge prediction unit 30 can be connected to a temperature sensor 32 of the vehicle outside the device in order to use it to detect the outside temperature. The lower the outside temperature, the higher the minimum charge level is set. Alternatively, or in combination therewith, the device can comprise a radio receiver 32' or a wired interface via which weather forecasts can be detected, in particular forecast air temperatures for the current location of the vehicle and for the subsequent start of the journey.

[0041] The device 10 also has an operating strategy specification unit 40. This is connected downstream of the start prediction unit 20 and the minimum charge prediction unit 30. The operating strategy specification unit 40 is configured to determine an operating strategy that results in a charge level at the end of the trip or at the subsequent start of the trip that is at least as high as the minimum charge level.

[0042] Finally, the device 10 has a control unit 50 connected downstream of the operating strategy specification unit 40. The control unit 50 is configured to control the internal combustion engine 60 or the generator 70 according to the operating strategy. For this purpose, the device has outputs via which the internal combustion engine 60 or the generator 70, which are not part of the device 10, can be connected for control purposes. The generator 70 is driven by the internal combustion engine 60; for this purpose, a motion-transmitting connection exists, as shown. The generator has an electrical output connected to an on-board electrical system 80, in which a battery 82' is provided. Alternatively or additionally, a battery can be connected to the generator 70. The on-board electrical system 80 is also connected to the generator 70, but via a connection that is independent of a connection between the generator 70 and the battery 82.

Claims

[1] Method for operating a drive of a vehicle, the drive comprising an internal combustion engine (60), comprising the steps of: Determining an expected end of the journey (tA) or a subsequent start of the journey (tNS) of the vehicle by estimating the expected end of the journey (tA) and / or the subsequent start of the journey (tNS) based on stored usage data of the vehicle or by entering the expected end of the journey (tA) and / or the subsequent start of the journey (tNS) at a user input interface (22''); Determining a minimum state of charge (S) of a battery (82) of the vehicle which it should have at the end of the journey (tA) or at the subsequent start of the journey (tNS), by specifying a higher minimum state of charge (S) at a low performance given by low temperatures than at comparatively higher temperatures; Operating the internal combustion engine (60), which is configured to charge the battery (82) by means of a generator (70), according to an operating strategy by means of which a state of charge (I1, I2, I3) resulting from the operating strategy at the end of the journey (tA) or at the subsequent start of the journey (tNS) is at least as great as the minimum state of charge (S); wherein the minimum state of charge (S) is determined based on meteorological data representing a temporal progression of an air temperature, based on received data, which represent a forecast air temperature at the determined end of the journey (tA) or at the subsequent start of the journey (tNS), or based on a combination thereof. [2] Method according to claim 1, wherein the usage data are specific to a driver, a respective battery state, a day of the week, a time of day, a season, an entered route, an entered destination and / or a location of the vehicle, or the expected end of the trip (tA) and / or the subsequent start of the trip (tNS) are received via a user input interface (22''). [3] Method according to one of the preceding claims, wherein the minimum state of charge (S) is determined on the basis of a predetermined relationship between the minimum state of charge (S) and a predicted temperature at the subsequent start of travel (tNS), wherein the minimum state of charge (S) is greater at a lower temperature than at a comparatively higher temperature. [4] Method according to claim 3, wherein the dependency between the minimum state of charge (S) and the temperature increases with decreasing temperature with an increasing gradient. [5] Method according to one of the preceding claims, wherein the operating strategy which defines the operation of the internal combustion engine (60) until the end of the journey is reached, - a charging rate is taken into account according to which the battery (82) is charged by the internal combustion engine (60) by means of the generator (70), - the end of the journey (tA) is taken into account, - the time until the end of the journey (tA) is taken into account, - a distance to the end of the journey is taken into account, - an estimated electrical consumption until the end of the journey (tA) is taken into account, - takes into account consumption for each subsequent run after the journey, - Road condition information and / or traffic condition information for the route ahead up to the end of the journey is taken into account, and / or - a predicted battery temperature at the end of the journey (tA) is taken into account. [6] Method according to one of the preceding claims, wherein the battery (82), the minimum charge state (S) of which is determined, supplies energy for starting the internal combustion engine (60) at the start of the journey, supplies an on-board electrical system (80) of the vehicle with energy during the journey and when parked, and / or supplies energy for the traction of the vehicle during operation of the vehicle. [7] Method according to one of the preceding claims, wherein the operating strategy is defined on the basis of an operating time of the internal combustion engine (60), which is the longer the greater the difference between a current state of charge (I1, I2, I3) and the minimum state of charge (S), wherein the state of charge at the end of the journey (tA) resulting from the operating strategy is predicted on the basis of a product of the operating time and a charging rate of the generator (70) and the battery (82) less a predicted amount of energy that will be absorbed by electrical consumers of the vehicle until the end of the journey, and starting from a current state of charge. [8] Method according to one of the preceding claims, wherein the function of electrical consumers which are not safety-relevant for the operation of the vehicle is restricted if the sum of a current state of charge and an amount of electrical energy which results from the operating strategy deviates downwards from the minimum state of charge (S) by more than a predetermined tolerance value. [9] Device (10) for controlling a drive of a vehicle, wherein the drive comprises an internal combustion engine (60), the device comprising: - a user input interface (22'') configured to input an expected end of the journey (tA) or a subsequent start of the journey of the vehicle (tNS) or a start prediction unit (20) configured to determine an expected end of the journey (tA) or a subsequent start of the journey of the vehicle (tNS), wherein the start prediction unit (20) is configured to estimate the expected end of the journey (tA) and / or the subsequent start of the journey (tNS) by estimating the expected end of the journey (tA) and / or the subsequent start of the journey (tNS) on the basis of stored usage data of the vehicle; - a minimum charge prediction unit (30) configured to determine a minimum charge state (S) of a battery (82, 82') of the vehicle, which the battery should have at the end of the journey (tA) or at the subsequent start of the journey, on the basis of meteorological data representing a temporal profile of an air temperature, on the basis of received data representing a predicted air temperature at the determined end of the journey (tA) or at the subsequent start of the journey (tNS), or on the basis of a combination thereof, wherein the minimum charge prediction unit (30) is configured to determine the minimum charge state (S) by specifying a higher minimum charge state (S) at a low performance level, which is given by low temperatures, than at comparatively higher temperatures; - an operating strategy specification unit (40) which is connected downstream of the start prediction unit (20) and the minimum charge prediction unit (30) and is designed to determine an operating strategy which results in a charge level at the end of the journey or at the subsequent start of the journey which is at least as high as the minimum charge level (S); and - a control unit (50) which is connected downstream of the operating strategy specification unit (40) and which is configured to control the internal combustion engine (60) and / or the generator (70) according to the operating strategy.

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